Preparation of proteinaceous soybean material using isopropanol



Patented Apr. 14, 1953 PREPARATION or raorrmscsoos sor- BEAN MATERIAL USING ISOPROPANOL Paul A. Belter, Pekin, Allan K. Smith, Harold J. ,Deobald, and Philip A. Singer, Peoria, 111., and Arthur C. Beckel, deceased, late of Peoria, 111.,

by Elmer F. Gury,

administrator, Peoria, 111.,

assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Application May 16, 1950, Serial No. 162,381

1 Claim.

(.Granted under Title 35.15.18; Code (1952,),

see. 266) This application ismade under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented in any country, may be manufactured and used by or for the Government of the United- States of America for governmental purposes throughout the world without the payment to us of any royalty thereon.-

Thisinvention relatesto methods for preparing aproteinaceous product from soybeans. More particularly, the invention relates to producing a gelable material from soybeans from which the oil'has been extracted;

the production of soybean oil soybeans are usually cracked and passed through flakingrolls and the flaked beans are then extracted with an oil solvent, suchas hexane, petroleum ether, orother light hydrocarbon, alkanols, trichlorethyleneand the like. The residual material comprises protein, fiber, and a minor proportion of various natural constituents of the original bean.- Depending upon the oil solvent used, the particular constitution of the residual material varies considerably as to the minor components.

In application Serial No. 782,941, now Patent No. 2,495,706 filedv October 29,1947, by De Vo'ss, Beckel and Belter, a process is described by-whichsoybean: residual material is freed from alcohol solubles and subsequently extracted with water.

The water extraction. separates a proteinaceous' material, aqueous dispersions; of which are capableof forming irreversible gels when heated; The proteinaceous content of the solids ranges from 50. percent to 60 percent. In application Serial No. 68,442, filed December 31', 1948, by 'Beckel and Belter, there; is described the use of such protein aceous soybean material as a-remoi'stening adhesive. In application SerialNo. 85,712, filed April 5, 1949, by Beckel, Cowan and Belter, now Patent No. 2,600,388, issued June 16, 1952, the heat-sealing properties of the material are described.

This invention has among its objects a process whereby soybean residual. material iromoil extraction processes may be treated continuously to remove the alcohol solubles efliciently and at low cost. Still. another object is to provide a process whereby hexane extract'ed' or petroleum ether-extracted soybean flakes may be washed with isopropanol to prepare. them for subsequent aqueous, extraction to produce gelable material and; to provide a process: having. certain advantages comparedwith the similar process using ethanol as described and claimed in copending application Serial No. 161,482 filed May 11, 1950 by Belter, Beckel and Smith.

It has been discovered that soybean material from which the oil has been extracted, may be washed or extracted by means of isopropanol to remove antige'lling constituents and, that, moreover, the miscella from the washing or extracting' may be subjected to a simple treatment for removing theextractable material therefrom, and subsequently returned continuously to extract fresh soybean material. This step or operation in general is based upon our discovery that the constituents removed by washing or extracting with isopropanolhave i du'd solubility in iS'O- propanol at reduced temperature. Separation is accomplished by cooling the miscella to: 20

C. or lower to efie'ct' precipitation ofinsoluble material and subsequently removing the precipitated material. 7

Since the cooling step does not eiie'ct removalor absolutely all extracted materialthere is acertain buildup of alcohol solubles in the recycling/ solvent. We have discovered that thesebuilt-up-materials never reach a deleterious c0n-= centration since the recycling solvent at final equilibrium conditions is stillan efficient extraction agency for removing antigelling. constituents. The final equilibrium is reached when the amount of built-up solubles is deposited on the wet flakes in the drier at a rate equal to their removal from the flakes in the extractor.

The soybean material utilized in this process, in particular hexane-extracted flakes, should be produced by flaking and oil extracting processes that avoid excessive temperatures. If, especially during the crushingv or flaking operations, exces-- sive temperatures are encountered, there is danger of. heat denaturing the protein. It is important that this be-avoided since denaturationof the proteinwill notproduce satisfactory gelling material.

In general, for the washing step isopropanol may; be used: within the range of percent aque-* ous' solutions upto absolute, and to percent solutions: are preferred. In a continuous process: thesolvent to flake ratio is preferably within the range: oi 5 to 131 on a weight basis although greater or less ratios: may be employed. The temperature of extraction may vary from room temperature lip-11095 0., preferably 5 to 10 C. above room temperature, and the-time of contact ranges from 15- minutes to" 1 hour. At

several degrees above room temperature and? higher the antigelling constituents are readily soluble in isopropanol and no particular difiiculty is experienced in agitation, contact times, etc.

Consequently, the extraction may be carried out.

either concurrently or countercurrently, and only enough agitation to insure contact of each flake with the solvent for a substantial period of time. In general, when operating at preferred temperatures we employ a temperature differential of C. or more between extraction and cooling of the extract, but, of course, 'the extracting temperatures should be confined to the range of 25 to 85 C. and the cooling temperatures to the range of 20 C. and lower.

For practical reasons it is preferred to carry out the extraction countercurrently. After extraction the flakes are conveyed to a drier where the residual solvent is recovered and any nonvolatile constituent still held in solution by the solvent is deposited on the flakes. Theextract is pumped to a cooler where it is cooled to room temperature or below and allowed to settle or otherwise subjected to separatory treatment for removing the precipitated material. It may then be recirculated to the extractor preferably after having been brought to the temperature prevailing therein.

. The water extract product obtained from isopropanol-washed flakes forms gels in substantially the same manner as that obtainable using ethanol or methanol, and its adhesive properties closely resemble those of the ethanol product. Although the isopropanol product exhibits differences in some properties, it nevertheless possesses certain important advantages. For example, it may be produced at considerably less cost due to the favorable price differential of isopropanol over ethanol. Furthermore, all inconveniences involved in governmental alcohol tax regulations are avoided. These advantages accruing from the use of isopropanol are all the more important since those practical properties of adhesiveness, which it possesses in excellent degree, are of great economic significance. The following specific example illustrates the invention. Parts are by weight unless otherwise specified.

Example An extraction apparatus was employed consisting of an extraction chamber having provision for feeding flakes and solvent. The flake feedconsisted of an endless screen conveyor disposed so as to pass through a zone of counterflowing solvent. The rate of feeding and time of contact with solvent could be controlled by varying the speed of the conveyor and by adjusting the level of the solvent in the extraction zone. The rate of solvent entering the extraction zone was controlled by a variable speed pump.

Isopropanol (90 percent) and flakes were fed to the apparatus in the ratio of 2 to 1 by weight. The apparatus was adjusted to provide a contact time of minutes, and the temperature of the extraction was held at 30 C. The extract,

or miscella, leaving the extractor, was cooled to approximately 4 0., allowed to settle and the supernatant solvent recycled. After the first complete cycle the solvent emerging from the extractor was again cooled and separated from precipitated solids in the same manner as before The run was continued until the total solubles concentration in and recycled a second time.

the recirculated isopropanol solvent had become constant. Fresh make-up isopropanol was added periodically to compensate for process losses and water.

to replace the solvent entrained by the wet fiakes leaving the extractor. During the recycle period, samples or fiakes emerging from the extractor were tested periodically and found capable of producing the gelable material by extraction with water.

The spray dried aqueous extract of these flakes is capable of forming gels when dispersed in For example, a double or triple extract of flake samples taken at intervals throughout the process of the example was heated. The temperature of heating may vary from 150 F. to boiling and the concentration of solids in the dispersion to be gelled may vary from 10 percent and higher. The extract when employed as a remoistening or heat sealing adhesive produces results comparable to those described and claimed in the copending applications previously referred to.

What is claimed is:

In a method for removing anti-gelling substances from oil-free soybean material containing undenatured soybean protein by extracting said material with an alcohol solvent for such impurities and subsequently separating the residual soybean material from the alcoholic extract, the improvement comprising extracting said material with isopropanol solvent within the range of 50 percent aqueous isopropanol to absolute isopropanol, the ratio of isopropanol solvent being five to one part of solvent for each part of said material, for a period of fifteen minutes to one hour and at a temperature of between room temperature and 0., separating the extract containing the anti-gelling substances, coolingv the separated extract to a temperature below 20 C. and at least 10 C. below the temperature of extraction to cause partial precipitation of extracted material, separating the precipitated material, permitting the remainder of the extracted materials to remain dissolved in the isopropanol solvent, recycling the said isopropanol solvent containing dissolved materials without further purification to extract more oil-free soybean material, and repeating the said steps of cooling the extract, separating precipitated materials and recycling the isopropanol containing dissolved materials, until an equilibrium is reached in which the built-up solubles are deposited on the solvent-wet soybean material leaving the extraction process at a rate substantially equal to the rate of their removal from the oil-free soybean material in the extraction step, make-up isopropanol being added periodically to compensate for process losses and to replace solvent entrained with the extracted soybean material leaving the extraction step.

PAUL A. BELTER. ALLAN K. SMITH. HAROLD J. DEOBALD. P. A. SINGER.

ELMER F. GURY,

Administrator of the estate of Arthur C. Beckel,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS 

